To begin, it is noted that the first known creation of two micron diameter or less, high aspect ratio, (eg. Depth/Diameter greater than 7.0), holes was achieved using femto second laser pulses. Further the usefulness of said holes is only recently being explored, particulalry by the semiconductor industry as it strives to achieve ever smaller size and lower operating power devices. The machining of materials using laser beams is known. For instance a Patent to Mourou et al, U.S. Pat. No. 5,656,186 describes the use of laser pulses which are characterized by having a pulse width equal to or less than a characteristic value, and focusing said laser pulses on or below the surface of a material. The characteristic pulse width is determined by noting a rapid and distinct change in slope of fluence breakdown threshold vs. laser pulse width. U.S. Pat. No. 6,285,002 to Ngoi et al. describes a three-dimensional micro-machining system comprising application of a spatial filter to fashion laser pulses. U.S. Pat. No. 5,787,102 to Alexander et al. describes use of a periodically structured non-linear material to generate second harmonics in a laser system. U.S. Pat. No. 5,761,111 to Glezer describes application of ultrashort laser pulses in forming 2D and 3D optical information storage in transparent materials. U.S. Pat. No. 6,313,461 to McClelland et al. describes detection of photoelectrons ejected from the surface of a material being machined to image magnetic and/or spectroscopic features of the surface of a sample. A Patent to Chin et al., U.S. Pat. No. 5,862,845 describes use of an ultrafast intense laser for processing lignocellulosic materials. Use of pulses of less than 10−9 sec. and having peak intensity of at least 1011 w/cm2 is described. In the context of the presently disclosed invention, a very relevant Patent is U.S. Pat. No. 6,337,479 to Kley. Said 479 patent describes the use of a scanning probe microscope probe to sweep away debris particles on a materials surface caused by laser machhining thereof. The Kley 419 patent is particularly relevant as it identifies the problem caused by particles which become dislodged and accumulate on a material's surface during laser-machining thereof by use of laser pulses caused to impinge thereupon.
Relevant Scientific Articles include:
“Breakdown Threshold and Plasma Formation in Femtosecond Laser-Solid Interaction”, Linde and Schyler, J. of the Opt. Soc. of America B., Opt. Phys. 13(1), (1996);
“Laser Ablation and Micromachining with Ultrashort Laser Pulses”, Lie et al., IEEE J. of Quantum Electronic 33(10) (1997);
“Femtosecond-Pulse Laser Microstructuring of Semiconductor Materials”, Kautek et al., Mat. Science Forum 173, (1995);
“Short-Pulse Laser Ablation of Solid Targets”, Momma et al., Optics Comm. 129, (1996);
“Experimental Study of Drilling Sub-10 n Holes in Thin Metal Foils With Femtosecond Laser Pulses”, Zhu et al., Appl. Surf. Sci. 152, (1999);
“Machining of Sub-Micron Holes Using a Femtosecond Laser at 800 nm”, Pronko et al., Optics Comm. 114, (1995);
“Ablation of Submicron Structures on Metals and Semiconductors by Femtosecond uv-Laser Pulse”, Simon et al., Appl. Surf. Sci. 109-110, (1997);
“Self-Modulation and Self-Focusing of Electromagentic Waves in Plasmas”, Max et al., Phys. Rev. Letters 33(4), (1974;
“Self-Modulation and Self-Focusing of Electromagentic Waves in Plasma”, Borisov et al., Physical Rev. A 45(8), (1992);
“Measurable Signatures of Self-Focusing in Underdense Plasma”, Gibbon et al., Phys. of Plasma, 2(4), (1995);
“Dynamics of Subpicosecond Relativistic Laser Pulse Self-Channeling in an Underdense Preformed Plasma”, Phys. Rev. Lett., 80(8), (1998);
“Evolution of a Plasma Waveguide Created During Relativistic-Ponderomotive Self-Channeling of an Intense Laser Pulse”, Chen et al., Phys. Rev. Let. 80(12), (1998);
“Relativistic Nonlinear Optivcs the Second Wind of Nonlinear Optics”, Mourou et al., Ultrashort Laser Workshop for DOD Applications, NSF-Center for Ultrafast Optical Science University of Michigan, (March 2000);
“Breakdown Threshold and Plasma Formation in Femtosecond Laser-Solid Interaction”, Linde et al., J. of the Opt. Soc. of America B., Opt. Phys. 13(1), (1996);
“Microstructuring of Silicon with Femtosecond Laser Pulses”, Her et al., Appl. Phys. Lett. 73(12), (1998).
Even in view of the existing art, there is identified a need for system and method means which can be applied to conveniently avoid accumulation of dislodged particles upon the surface of a material being micro machined by application of laser pulses thereto. The disclosed invention provides new, novel and useful solution means to said problem.